1. Field of the Invention
The present invention relates to a method for producing a string-shaped bacteria bed used for sewage or wastewater treatment, and more particularly, to a method for producing a string-shaped bacteria bed having high holding capacity of bacteria colony with very simplified installations.
2. Description of the Prior Art
The string-shaped bacteria bed is formed with many loops of fiber for holding bacteria colony therein on the whole surface thereof, and is used for sewage or wastewater treatment in the aeration tank by forming a module consisting of prefabricated curtain arrangement supported in said tank by light weight beams at the top and the bottom of the curtain.
This type of bacteria bed is very useful in practice as follows.
(1) The string-shaped bacteria beds (elements) are arranged to form a curtain by spacing the same, and consequently the element volume can be changed easily. PA0 (2) Since the elements are installed in the tank by means of a hanging frame, installation is very easy. PA0 (3) The elements can be folded for shipment, thus reducing packing dimensions and transportation costs.
There are conventionally known method for producing a string-shaped bacteria bed, such as a method comprising steps of preparing a narrow strip of cloth having many loops of fiber on the obverse thereof, and stretching and twisting the the strip by a stretching and twisting machine to form a twisted or stranded mole-like string having many loops of fiber on the whole surface thereof. (Japanese laid-open patent publication No. 134965/74).
With such conventional method, however, various disadvantages are encountered: the twist or strand of the string gradually loosens even though the twisting is adequate, and consequently the holding capacity of bacteria colony in the string becomes lower, and moreover, the stretching and twisting machine is required for twisting, and thus the installations therefor become complicated.